Hi I am currently implementing quota for Slide.
In the mailling list, I read that slide developpers were interrested in including this feature into slide's kernel. So I'm searching feedback before going further in my implementation to be sure it feets slide's developpers needs and way of coding. I began the implementation following advices Dirk made on an email dated from august 2001 in which he was saying : - the more generic way to integrate quota is to do it into ContentInterceptor class - user's quota and bytes used can be stored into protected properties from user's node - the algorithm could be resumed as this : in preStoreContent method check if user has enougth space and put a lock on the user, in the postStoreContent method update bytes used and unlock user's node. - to deal with content removing, add a postRemoveContent method to the ContentInterceptor class. - what to do if clients don't send a contentLength ? - to allow webdav methods to indicate webdav clients the reason why the operation failed, ContentInterceptor class must throw a special exception that has to be catched by webdav methods to send webdav clients an insufficient storage error code (507) So here is the begin of an implementation that takes in account (almost) all these advices. I have added to package content a new Exception called InsufficientStorageException I think that the best place to add a parameter to enable quota is in the <configuration> section of the domain.xml file. This one is read by the NamespaceConfig class that instanciates the ContentInterceptors. I've added to the ContentInterceptor class a new contructor that has to be called by NamespaceConfig class if Domain.xml file tells to enable quota. Some questions I am asking myself : Why is there an array of contentInterceptor instances into NamespaceConfig class rather than a unique instance ? Some ContentInterceptor methods need a contentHelper and/or a lockHelper to do their job. What would be the best : to give them to constructor to initialize private properties or to give them as method argument ? Is postStoreContent method called if an exception has been raised by preContentStore method or someone else ? Which subject, type and expiration use to lock the user's node ? I think that with this token we can only use the user as subject but if the lock is put by the user, it can be kill by the user, isn't it ? With a lock on the user's node, user won't be able to perform any other operation ? What could be done with webdav clients that don't send a contentLength header ? What could be done better than it is in my code ? All remarks are welcome JP
/* * $Header: /home/cvs/jakarta-slide/src/share/org/apache/slide/content/ContentInterceptor.java,v 1.3 2001/05/14 09:19:32 remm Exp $ * $Revision: 1.3 $ * $Date: 2001/05/14 09:19:32 $ * * ==================================================================== * * The Apache Software License, Version 1.1 * * Copyright (c) 1999 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. 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IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * * [Additional notices, if required by prior licensing conditions] * */ package org.apache.slide.content; import java.util.Date; import java.util.Enumeration; import org.apache.slide.lock.*; import org.apache.slide.store.Store; import org.apache.slide.common.SlideToken; import org.apache.slide.common.ServiceAccessException; import org.apache.slide.security.AccessDeniedException; import org.apache.slide.structure.ObjectNotFoundException; import org.apache.slide.structure.LinkedObjectNotFoundException; /** * Slide content interceptor class. * * @author <a href="mailto:[EMAIL PROTECTED]";>Remy Maucherat</a> * @author <a href="mailto:[EMAIL PROTECTED]";>Jean-Philippe Courson</a> */ public class ContentInterceptor { // ----------------------------------------------------------- Constructors /** * Default Constructor with quota disabled. */ public ContentInterceptor() { this.quotaEnabled = false; } /** * Constructor to use to enable quota. * * @param usersPath Users nodes path. */ public ContentInterceptor(String usersPath) { this.quotaEnabled = true; this.usersPath = usersPath; } // ----------------------------------------------------- Instance Variables /** * Quota enabled ? */ private boolean quotaEnabled; /** * Users nodes path. */ private String usersPath; // ------------------------------------------------------ Protected methods /** * That method will be called just before storing content. * * @param token Slide's token * @param revisionDescriptors New node revision descriptors * @param revisionDescriptor New node revision descriptor * @param revisionContent New node revision content * @param contentHelper Content helper * @param lockHelper Lock helper */ protected void preStoreContent(SlideToken token, NodeRevisionDescriptors revisionDescriptors, NodeRevisionDescriptor revisionDescriptor, NodeRevisionContent revisionContent, Content contentHelper, Lock lockHelper) throws InsufficientStorageException, AccessDeniedException, ServiceAccessException, ObjectNotFoundException, LinkedObjectNotFoundException, ObjectLockedException { // quota enabled ? if(!quotaEnabled) return; // retrieve new content length long contentLength = revisionDescriptor.getContentLength(); if(contentLength <= 0) return; // retrieve user's bytesUsed and quota properties // build user's node uri String userUri = getUserUri(token); // retrieve user node revision descriptor NodeRevisionDescriptors userRevisionDescriptors = contentHelper.retrieve(token, userUri.toString()); NodeRevisionDescriptor userRevisionDescriptor = null; try { userRevisionDescriptor = contentHelper.retrieve(token, userRevisionDescriptors); } catch(RevisionDescriptorNotFoundException e) { // should never happen } // retrieve user node bytesUsed property NodeProperty property = userRevisionDescriptor.getProperty("bytesUsed"); if(property == null) throw new ServiceAccessException((Store)contentHelper, "Quota enabled but user "+userUri+" has no bytesUsed property"); long bytesUsed = Long.parseLong((String)property.getValue()); // retrieve user node quota property property = userRevisionDescriptor.getProperty("quota"); if(property == null) throw new ServiceAccessException((Store)contentHelper, "Quota enabled but user "+userUri+" has no quota property"); long quota = Long.parseLong((String)property.getValue()); // if user quota exhausted throws InsufficientStorageException if(bytesUsed+contentLength > quota) throw new InsufficientStorageException("Quota exhausted for user "+userUri); // lock user node // FIXME: WHICH TYPE OF LOCK (EXCLUSIVE ?, SUBJECT ?, LENGTH ?) Date expiration = new Date(System.currentTimeMillis()+3600000); NodeLock lock = new NodeLock(userUri, userUri, "/actions/read", expiration, false, true); try { lockHelper.lock(token, lock); } catch(ObjectIsAlreadyLockedException e) { // FIXME: WHAT SHOULD BE DONE HERE ? } } /** * That method will be called just after storing content. * * @param token Slide's token * @param revisionDescriptors New node revision descriptors * @param revisionDescriptor New node revision descriptor * @param revisionContent New node revision content * @param contentHelper Content helper * @param lockHelper Lock helper */ protected void postStoreContent(SlideToken token, NodeRevisionDescriptors revisionDescriptors, NodeRevisionDescriptor revisionDescriptor, NodeRevisionContent revisionContent, Content contentHelper, Lock lockHelper) throws AccessDeniedException, ServiceAccessException, ObjectNotFoundException, LinkedObjectNotFoundException, ObjectLockedException { // quota enabled ? if(!quotaEnabled) return; // update user's node bytesUsed properties updateBytesUsed(token, true, revisionDescriptor, contentHelper); // build user's node uri String userUri = getUserUri(token); // unlock user's node try { Enumeration locks = lockHelper.enumerateLocks(token, userUri, false); while(locks.hasMoreElements()) { NodeLock lock = (NodeLock)locks.nextElement(); if(lock.getSubjectUri().equals(userUri) && lock.getTypeUri().equals("/actions/read") && lock.isExclusive()) lockHelper.unlock(token, lock); } } catch(LockTokenNotFoundException e) { // to much time ellapsed, nothing we can do } } /** * That method will be called just after removing content. * * @param token Slide's token * @param revisionDescriptors New node revision descriptors * @param revisionDescriptor New node revision descriptor * @param revisionContent New node revision content * @param contentHelper Content helper */ protected void postRemoveContent(SlideToken token, NodeRevisionDescriptors revisionDescriptors, NodeRevisionDescriptor revisionDescriptor, NodeRevisionContent revisionContent, Content contentHelper) throws AccessDeniedException, ServiceAccessException, ObjectNotFoundException, LinkedObjectNotFoundException, ObjectLockedException { // quota enabled ? if(!quotaEnabled) return; // update user's node bytesUsed properties updateBytesUsed(token, false, revisionDescriptor, contentHelper); } /** * That method will be called just after retrieving content. * * @param token Slide's token * @param revisionContent null when the descriptor is retrieved * @param revisionDescriptors null when the content is retrieved * @param revisionContent Node revision content */ protected void postRetrieveContent(SlideToken token, NodeRevisionDescriptors revisionDescriptors, NodeRevisionDescriptor revisionDescriptor, NodeRevisionContent revisionContent) { } // ------------------------------------------------------ Private methods /** * Method used to update user's node bytesUsed property. * * @param token Slide's token * @param addValue If set to true, new node contentLength is added else it is substracted * @param revisionDescriptor New node revision descriptor * @param contentHelper Content helper */ private void updateBytesUsed(SlideToken token, boolean addValue, NodeRevisionDescriptor revisionDescriptor, Content contentHelper) throws AccessDeniedException, ServiceAccessException, ObjectNotFoundException, LinkedObjectNotFoundException, ObjectLockedException { // retrieve new content length long contentLength = revisionDescriptor.getContentLength(); if(contentLength <= 0) return; // retrieve user's bytesUsed properties // build user's node uri String userUri = getUserUri(token); // retrieve user's node revision descriptor NodeRevisionDescriptors userRevisionDescriptors = userRevisionDescriptors = contentHelper.retrieve(token, userUri.toString()); NodeRevisionDescriptor userRevisionDescriptor = null; try { userRevisionDescriptor = contentHelper.retrieve(token, userRevisionDescriptors); } catch(RevisionDescriptorNotFoundException e) { // should never happen } // retrieve user's node bytesUsed property NodeProperty property = userRevisionDescriptor.getProperty("bytesUsed"); if(property == null) throw new ServiceAccessException((Store)contentHelper, "Quota enabled but user "+userUri+" has no bytesUsed property"); long bytesUsed = Long.parseLong((String)property.getValue()); // computes new bytesUsed value if(addValue) bytesUsed = bytesUsed+contentLength; else { bytesUsed = bytesUsed-contentLength; if(bytesUsed < 0) bytesUsed = 0; } // update user's node totalBytes properties userRevisionDescriptor.setProperty("bytesUsed", Long.toString(bytesUsed), true); try { contentHelper.store(token, userUri, userRevisionDescriptor, null); } catch(RevisionDescriptorNotFoundException e) { // should never happen } catch(RevisionNotFoundException e) { // should never happen } } /** * Method used to build user's node uri. * * @param token Slide's token * * @return user's node uri */ private String getUserUri(SlideToken token) { StringBuffer sb = new StringBuffer(usersPath); sb.append("/"); sb.append(token.getCredentialsToken().getPublicCredentials()); return sb.toString(); } }
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